Stabilization of alpha-lipoic acid by complex formation with octenylsuccinylated high amylose starch.

The thermal and oxidative stability of alpha-lipoic acid (ALA) in aqueous dispersions containing beta-cyclodextrin (CD), native high amylose (HA) and octenylsuccinylated high amylose (OS) starches (0.1% ALA and 1.0% CD or starch solids) were compared. Both native and modified starches increased the stability of ALA against thermal degradation and oxidation at higher degrees than CD. The OS was more effective in stabilizing ALA than HA. The ALA loss in the dispersions occurred mainly in the supernatant, suggesting that the complex formation of ALA with amylose played a key role in the stabilization. In an in vitro digestion test, the release of ALA from OS dispersion was less than that of HA dispersion, indicating that ALA complexed with OS amylose was most stable against digestion. The octenylsuccinylated high amylose starch was an effective protecting agent for ALA in aqueous media, as well as a delivery carrier for ALA in digestive tract.